Field of Invention
This invention relates to clasps and closures and more particularly to single use fasteners having a head portion defining a slot at one end of an elongate strap that loops over and irremovably engages in the slot.
Background and Description of Prior Art
Fasteners of the instant type are commonly referred to as “cable ties” and are well-known for fastening items together such as container latches, bundles of wire and groupings of flexible tubular members, Typically the fastener is threaded through adjacent aligned holes defined in portions of a container that move distally from one another when the container is opened, or the fastener is extended circumferentially around the bundle of wires or groupings of items to secure the wires or groupings of items in proximity to one another.
Generally, cable ties have an elongate strap that is tapered at one end portion. Opposite the tapered end portion is a dimensionally larger head portion defining a slot through which the tapered end portion of the elongate strap may be inserted. A resiliently displaceable pawl is carried within the slot and the pawl engages with one of a plurality of transverse grooves defined in the elongate strap.
Cable tie type fasteners are typically single use items. Once the elongate strap is inserted through the slot and the pawl has engaged with the parallel transverse grooves, the elongate strap cannot be withdrawn from the slot without breaking the pawl, breaking the elongate strap or otherwise physically destroying the cable tie. Once the cable tie has been broken, it cannot be repaired or re-affixed.
The inability to remove a fastened cable tie without physically or functionally destroying the cable tie is both a desirable feature and a drawback.
Because of theft single use nature, cable ties are commonly used in apparatus that require security, such as the transport of money, pharmaceuticals and other valuable commodities. When a container of the commodity is filled, closed and thereafter secured with a cable tie, it can reasonably be assumed that if the container, and in-place cable tie, are undisturbed when the container is later opened, and that the container and contents have not been tampered with, Conversely, if the container or the cable tie have been broken, it can reasonably be assumed that the original contents of the container have been tampered with and are no longer in the same condition and perhaps same quantity, as they were when the cable tie was originally secured to the container.
In the pharmaceutical industry, cable ties are used to securely close pharmaceutical tote boxes. A tote box arriving with the cable tie broken or damaged can be rejected or at a minimum closely inspected. In other instances it is desirable to have a strong and secure fastener that may be quickly engaged/fastened when necessary and also quickly and easily removed, for example in outdoor activities such as camping where securing items together is necessary, such as joining tarps together or securing items to tree branches. Further, in law enforcement activities such fasteners may be used as restraints for persons being detained. In both such examples of use, the strong and secure fastener is required, but being able to quickly and easily remove/destroy the fastener is also necessary.
By the same token, one of the drawbacks of cable ties is that they are difficult to break. Cutting the cable tie with a wire cutter or knife poses a risk of unintentionally damaging the item being secured and requires use of a tool. Breaking the cable tie by inserting an elongate rigid object, such as a screwdriver, through the looped elongate strap and twisting the inserted object to break the cable tie is even more likely to damage the item secured by the cable tie.
There are known “tear away” cable ties designed for easy removal. Known tear away cable ties have a planar rectilinear tag adjacent the head portion and define a “scored” or “weakened” area between the tag and the head portion. Pulling on the rectilinear tag portion tears the cable tie at the “scored/weakened” area detaching the head portion from the strap portion without use of a tool or cutting device. Unfortunately, shearing forces such as those used to intentionally break known “tear away” cable ties may be inadvertently applied to the cable tie if the rectilinear tag is inadvertently caught between two surfaces that move relative to one another, such as a top and a bottom or adjacent sides of adjacent containers being transported in a vehicle. Any movement wherein one container moves along and across an adjacent container may provide the necessary shearing motion to break known tear away cable ties. Further, known “tear away” cable ties with rectilinear tags have sharp edges and corners, they are not aesthetically pleasing, they are difficult to package in bundles because the rectilinear tags “catch” on one another and they can be difficult to manufacturer.
What is needed is a durable secure cable tie type fastener that cannot be removed without destroying the cable tie, but can be intentionally removed without resorting to took and without damaging the item being secured. The cable tie must be easy to use, not subject to unintentional breakage, aesthetically pleasing and easy to manufacture and package.
Our improved twist off cable tie fastener addresses various of these drawbacks by providing a product that is strong and secure and is less likely to be inadvertently and unintentionally broken, but can also be broken without use of took when desired. When broken, the fact the cable tie has been broken is un-mistakenly identifiable.
Our invention is an improved twist off cable tie type fastener comprising an elongate strap of flexible yet strong plastic, preferably polypropylene, that defines a plurality of parallel adjacent transverse teeth in the elongate strap. One end portion of the elongate strap is tapered to a rounded tip to ease insertion through a through channel defined in a head portion integrally carried at the end of the elongate strap opposite the tapered tip.
The through channel carries an angled flexing arm having plural angular teeth that cooperatively engage with the transverse teeth defined in the elongate strap. The angulated teeth carried by the flexing arm are configured to prevent the elongate strap from being withdrawn from the through channel once inserted therethrough and a channel frame around the through channel prevents insertion of took that might be used to tamper with the flexing arm.
The head portion defining the through channel is generally rectilinear in peripheral configuration and structurally carries two opposing spaced apart planar wings on its side portions with the two wings oriented parallel to an axis of the through channel and perpendicular to the elongate strap. This orientation causes any excess length of the elongate strap that is drawn through the medial channel when the fastener is in use to extend outwardly between the two spaced apart wings which allows space saving and allows use of the fastener in locations with limited space.
A notch may be formed in the elongate strap immediately adjacent the head portion to ensure fracturing occurs at a predetermined location. The notch does not negatively affect the axial or tensile strength of the cable tie.
The wings carried by the head portion facilitate grasping and twisting of the head portion by a user. The twisting action which is along a minor transverse axis of the elongate strap and perpendicular to a longitudinal axis of the elongate strap concentrates breaking forces on the elongate strap immediately adjacent the head portion. The perpendicular rotation of the wings breaks the cable tie allowing the cable tie's removal without tools and without damaging the item to which the cable tie was fastened. Further, limited rotational movement of the wings, of less than approximately one full 360 degree rotation is sufficient to fracture the cable tie fastener, and more preferably, less than approximately 180 degrees of rotation is sufficient to fracture the cable tie fastener, and still even more preferably, approximately 90 degrees of rotation is sufficient to fracture the cable tie fastener.